The study of 4kF CDW in a one-dimensional system, (DMe-DCNQI)2Li1−xCux

We systematically study transport and optical properties of charge-transfer salts, (DMe-DCNQI)2Li1−xCux (0≤x≤1). In the optical studies, we found the two absorption bands, one attributable to collective excitations associated with 4kF CDW (A-band) and the other to single-particle excitations across the Peierls gap (B-band). The intensity of the former band is almost constant for x≤0.29 and steeply increases for x≥0.39. The latter band appears around 3000 cm−1 for 0≤x≤0.14, and shifts downward for x≥0.17.